Inboxbooster lands seed funding after fixing YCombinator’s email problems

Over 3.5 million emails are sent every second and yet nearly 85% will be destined for spam folders including opt-in emails and even payment notifications. To address this challenge, Inboxbooster launched from stealth with a $1m pre-seed funding round to help email senders get their comms into the inbox of their audience. The round includes participation from Y Combinator, and angels Francois Lagunas, Razvan Roman, Julien Lemoine and Ralph Gootee.

What is the product offering of Inboxbooster?

Built on a dataset of 100 million emails, Inboxbooster detects and fixes email in spam folders. The Inboxbooster resolution test confirms the issue by querying spam filters to understand what is wrong with the emails and then build a step-by-step guide such as removing specific words, changing the form of some URLs or steps to improve a poor domain reputation.

The tool also analyzes the delivery infrastructure and offers solutions, this includes evaluating the reputation of the domain and the sending IP while analyzing the email content to flag what part is triggering the spam filter. Inboxbooster builds a personalized step-by-step guide to make emails compliant with filter requirements and get it back to the primary inbox.

Inboxbooster co-founder Nicolas Toper said: “In the world of emails, spam is the equivalent of the bottom of the ocean. No one wants their email to end up in spam yet, a number of these end up there and avoiding it can be more difficult. Inboxbooster tells you why you’re in the spam or promotion folder and what to do to move back to the inbox. Email is the only open communication left and it’s important to preserve this and make it accessible to all.”

“Large companies can deploy expensive consultants and remedy their issues but we are filling a significant gap in the market for others because no other solution fixes the problem in the same way and we’re redressing the competition. And this affects everyone sending emails, not marketers. For example, we fixed the payment notifications for a mortgage provider sending approval notices. This is a real and really painful issue for many,” Toper further said.

How was the idea born?

The Inboxbooster journey began in 2017 when Nicolas Toper was experimenting with email. He connected with co-founder Marcus Engene at the Summer 2020 Y Combinator 3-month programme. Whilst testing and building their product, they noticed that Y Combinator’s weekly newsletter on how to build startups was landing in spam and promotion on Gmail.

Having applied their model on it, Inboxbooster moved the newsletter  back to the primary inbox and improved their click rate by 35%. Inboxbooster detected the words of the email that were sending the email outside of the inbox and improved the subscriber targeting.

Today, Inboxbooster already has over 3,000 users. Prior to Inboxbooster, Toper founded CritSend where he helped clients send 50 billion emails. While Marcus Engene founded Pond5, the media marketplace, backed by Accel and Stripe and later acquired for over $200m.

Nicolas Toper said: “We are going to make a deeper dive into how software connected to email will work in the future and explain how the spam AI filter is deciding to do and why.”